I’m guessing annual ryegrass, but I’m no expert.

I think it is more likely to be tall fescue. Annual ryegrass is usually lighter green. The underside of annual ryegrass leaves is shinier than that of tall fescue and has a typical shape with a slight keel in the middle. The underside of tall fescue leaves is smooth or slightly unevenly corrugated. The still closed panicle also does not look like annual ryegrass.

Short hairs on the leaf edge in the collar region are a typical characteristic:

 

Thank you 2L8! There are so many little details in all these grasses … and as I said, I’m no expert! Now, if it is in fact tall fescue, is it actually a weed? Isn’t tall fescue one of the grasses commonly found in cool season seed blends? Would you recommend I do anything about them or just let the rest of the grass catch up and hope it all blends together at some point?

 

To add to this…

Tall Fescue also usually feels much stiffer than Annual ryegrass, and its blades are usually shorter and darker green too. Stems are longer and plant crown is higher.

The rhizome in your photo can also be a feature of Tall Fescue. Just might want to consider Quackgrass as well…a type of wheat grass that has more rhizomes than Talk Fescue and looks similar to the two other grasses…usually considered a weed.

 

Now, if it is in fact tall fescue, is it actually a weed? Isn’t tall fescue one of the grasses commonly found in cool season seed blends?

Tall fescue, more precisely Turf Type Tall Fescue (TTTF) is actually often the main component of cool season seed mixtures.

You wrote that you used “KBG Blend”. That sounds to me like a mixture of different KBG (Kentucky Blue Grass) varieties. Many cool season seed mixtures contain approx. 90 % TTTF and 10 % KBG. You should be able to find information about this on the packaging.

The fact that tall fescue is an impurity of KBG seeds should not actually occur. The seeds are about four times heavier and correspondingly larger than those of KBG. Should be easy to separate. On the other hand, I have already found smaller seeds in TTTF.

The rhizome in your photo can also be a feature of Tall Fescue.

Yes, it could be. It could also be a rhizome of KBG that has grown through the roots of the plant shown in the second picture. Sometimes the individual plants are not so easy to separate. KBG rhizomes:

 

Thank you 2L8 and Green! Looks like I have some more learning to do!